At this stage, I think we can say that your system has been deeply harmed... You have a chance to repair your system, however. At least I hope. Note that, as zypper is a really central library on SUSE systems, it may not work... Note also that I use an openSUSE, not a SLES, but things should be quite similar...

What you can try is to reinstall the libzypp library (or zypper, but it should be libzypp. At least, I hope). Get it manually from the repository you use ordinary... and hope you won't have a version problem later...

Once it's done, try to install it using directly rpm. Force the installation if needed. If rpm is not broken, it may work... If it does, make your update again, in order to be sure to use a coherent system.